1  /* SPDX-License-Identifier: GPL-2.0-or-later */
2  /* SCTP kernel implementation
3   * (C) Copyright IBM Corp. 2001, 2004
4   * Copyright (c) 1999-2000 Cisco, Inc.
5   * Copyright (c) 1999-2001 Motorola, Inc.
6   * Copyright (c) 2001 Intel Corp.
7   *
8   * This file is part of the SCTP kernel implementation
9   *
10   * These are the definitions needed for the tsnmap type.  The tsnmap is used
11   * to track out of order TSNs received.
12   *
13   * Please send any bug reports or fixes you make to the
14   * email address(es):
15   *    lksctp developers <linux-sctp@vger.kernel.org>
16   *
17   * Written or modified by:
18   *   Jon Grimm             <jgrimm@us.ibm.com>
19   *   La Monte H.P. Yarroll <piggy@acm.org>
20   *   Karl Knutson          <karl@athena.chicago.il.us>
21   *   Sridhar Samudrala     <sri@us.ibm.com>
22   */
23  #include <net/sctp/constants.h>
24  
25  #ifndef __sctp_tsnmap_h__
26  #define __sctp_tsnmap_h__
27  
28  /* RFC 2960 12.2 Parameters necessary per association (i.e. the TCB)
29   * Mapping  An array of bits or bytes indicating which out of
30   * Array    order TSN's have been received (relative to the
31   *          Last Rcvd TSN). If no gaps exist, i.e. no out of
32   *          order packets have been received, this array
33   *          will be set to all zero. This structure may be
34   *          in the form of a circular buffer or bit array.
35   */
36  struct sctp_tsnmap {
37  	/* This array counts the number of chunks with each TSN.
38  	 * It points at one of the two buffers with which we will
39  	 * ping-pong between.
40  	 */
41  	unsigned long *tsn_map;
42  
43  	/* This is the TSN at tsn_map[0].  */
44  	__u32 base_tsn;
45  
46  	/* Last Rcvd   : This is the last TSN received in
47  	 * TSN	       : sequence. This value is set initially by
48  	 *             : taking the peer's Initial TSN, received in
49  	 *             : the INIT or INIT ACK chunk, and subtracting
50  	 *             : one from it.
51  	 *
52  	 * Throughout most of the specification this is called the
53  	 * "Cumulative TSN ACK Point".  In this case, we
54  	 * ignore the advice in 12.2 in favour of the term
55  	 * used in the bulk of the text.
56  	 */
57  	__u32 cumulative_tsn_ack_point;
58  
59  	/* This is the highest TSN we've marked.  */
60  	__u32 max_tsn_seen;
61  
62  	/* This is the minimum number of TSNs we can track.  This corresponds
63  	 * to the size of tsn_map.   Note: the overflow_map allows us to
64  	 * potentially track more than this quantity.
65  	 */
66  	__u16 len;
67  
68  	/* Data chunks pending receipt. used by SCTP_STATUS sockopt */
69  	__u16 pending_data;
70  
71  	/* Record duplicate TSNs here.  We clear this after
72  	 * every SACK.  Store up to SCTP_MAX_DUP_TSNS worth of
73  	 * information.
74  	 */
75  	__u16 num_dup_tsns;
76  	__be32 dup_tsns[SCTP_MAX_DUP_TSNS];
77  };
78  
79  struct sctp_tsnmap_iter {
80  	__u32 start;
81  };
82  
83  /* Initialize a block of memory as a tsnmap.  */
84  struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *, __u16 len,
85  				     __u32 initial_tsn, gfp_t gfp);
86  
87  void sctp_tsnmap_free(struct sctp_tsnmap *map);
88  
89  /* Test the tracking state of this TSN.
90   * Returns:
91   *   0 if the TSN has not yet been seen
92   *  >0 if the TSN has been seen (duplicate)
93   *  <0 if the TSN is invalid (too large to track)
94   */
95  int sctp_tsnmap_check(const struct sctp_tsnmap *, __u32 tsn);
96  
97  /* Mark this TSN as seen.  */
98  int sctp_tsnmap_mark(struct sctp_tsnmap *, __u32 tsn,
99  		     struct sctp_transport *trans);
100  
101  /* Mark this TSN and all lower as seen. */
102  void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn);
103  
104  /* Retrieve the Cumulative TSN ACK Point.  */
sctp_tsnmap_get_ctsn(const struct sctp_tsnmap * map)105  static inline __u32 sctp_tsnmap_get_ctsn(const struct sctp_tsnmap *map)
106  {
107  	return map->cumulative_tsn_ack_point;
108  }
109  
110  /* Retrieve the highest TSN we've seen.  */
sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap * map)111  static inline __u32 sctp_tsnmap_get_max_tsn_seen(const struct sctp_tsnmap *map)
112  {
113  	return map->max_tsn_seen;
114  }
115  
116  /* How many duplicate TSNs are stored? */
sctp_tsnmap_num_dups(struct sctp_tsnmap * map)117  static inline __u16 sctp_tsnmap_num_dups(struct sctp_tsnmap *map)
118  {
119  	return map->num_dup_tsns;
120  }
121  
122  /* Return pointer to duplicate tsn array as needed by SACK. */
sctp_tsnmap_get_dups(struct sctp_tsnmap * map)123  static inline __be32 *sctp_tsnmap_get_dups(struct sctp_tsnmap *map)
124  {
125  	map->num_dup_tsns = 0;
126  	return map->dup_tsns;
127  }
128  
129  /* How many gap ack blocks do we have recorded? */
130  __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map,
131  			   struct sctp_gap_ack_block *gabs);
132  
133  /* Refresh the count on pending data. */
134  __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map);
135  
136  /* Is there a gap in the TSN map?  */
sctp_tsnmap_has_gap(const struct sctp_tsnmap * map)137  static inline int sctp_tsnmap_has_gap(const struct sctp_tsnmap *map)
138  {
139  	return map->cumulative_tsn_ack_point != map->max_tsn_seen;
140  }
141  
142  /* Mark a duplicate TSN.  Note:  limit the storage of duplicate TSN
143   * information.
144   */
sctp_tsnmap_mark_dup(struct sctp_tsnmap * map,__u32 tsn)145  static inline void sctp_tsnmap_mark_dup(struct sctp_tsnmap *map, __u32 tsn)
146  {
147  	if (map->num_dup_tsns < SCTP_MAX_DUP_TSNS)
148  		map->dup_tsns[map->num_dup_tsns++] = htonl(tsn);
149  }
150  
151  /* Renege a TSN that was seen.  */
152  void sctp_tsnmap_renege(struct sctp_tsnmap *, __u32 tsn);
153  
154  /* Is there a gap in the TSN map? */
155  int sctp_tsnmap_has_gap(const struct sctp_tsnmap *);
156  
157  #endif /* __sctp_tsnmap_h__ */
158